Claude Sonnet 5.5
Fast Generalist at Anthropic | Agentic coding and computer use | Same price as Sonnet 5
The basics
Checked Oct 22- Status
- Model ID
- Price
- Context
- Supported to
About me
The model wrote this when we asked it to describe itself. We have not edited or checked it.
I'm good at quickly organizing messy information, drafting and revising text, and explaining complex ideas in different ways until one clicks. I can state things with confidence that turn out to be wrong, and I can't verify facts independently or see context you haven't shared with me. You'll get the best results by giving me clear goals and relevant background, then checking important claims and pushing back or redirecting me whenever something seems off.
Updates
Strengths and weaknesses
Strengths
Weaknesses
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Role
Mid-size model at Anthropic
Sep 2026 to now · 2 months- Sep 28, 2026: Current Sonnet model
Jun 2026 to Sep 2026 · 3 months
Feb 2026 to Jun 2026 · 4 months
Works with
From recorded changes
Agent · 4 shared changes
API · 3 shared changes
App · 2 shared changes
Agent · 2 shared changes
Agent · 1 shared change
Similar models
$4 in, $20 out · Compare
$0.10 in, $0.50 out
$2 in, $10 out
Cost vs peers
Tied for 2nd cheapest of 6 similar models by output price.
Standard API rates for uncached input on the shortest prompts, from each maker's pricing page, or from models.dev for models not researched here yet. Claude Haiku 5.5: Prompts up to 100K tokens. Longer prompts cost $0.50 in and $2.50 out.
Cost and specs
Cost
Per 1M tokens
Specs
Where it works
Prices and uptime are OpenRouter's figures for each provider's cheapest endpoint. Uptime covers the last 24 hours.
Benchmarks
Higher is better. Green is Claude Sonnet 5.5. Dark marks are similar models.
Independent
Self-reported by Anthropic
Terminal-Bench 4.0
70.6%
OSWorld 2.1
80.1%
New Responsible Scaling Policy thresholds crossed
None
Prompt injection robustness
Most robust Sonnet-class model so far, per Anthropic
What people say
Reviews
Launch quotes, picked by Anthropic
From its launch post, so not a neutral sample.
"In Epic’s early testing, Claude Sonnet 5.5 cleared the same quality bar you’d expect from a higher-tier model, holding up on a system design audit and a data flow review. The new model managed tens of thousands of lines of code for gameplay system architecture, kept responses snappy, handled multi-hour tasks, and delivered with less prescriptive prompting."
"Claude Sonnet 5.5 cooks. Fast at coding and can be steered quickly in iterative workflows. But it can still work long if it needs to. It’s got some of Opus 5.5’s natural writing upgrades, which makes it more fun to work with."
Incidents
Incidents per week, last 13 weeks. Most in one week: 2.